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981.
Aoki S Bahk SY Chung KS Chung SH Funahashi H Hahn CH Hara T Hirata S Hoshino K Ieiri M Iijima T Imai K Ishigami T Itow Y Kazuno M Kikuchi K Kim CO Kim DC Kim JY Kobayashi M Kodama K Maeda Y Masaike A Matsuda Y Nagoshi C Nakamura M Nakanishi S Nakano T Nakazawa K Niwa K Okabe H Ono S Park IG Sato Y Shibuya H Shimizu HM Song JS Tajima H Takashima R Takeutchi F Tanaka KH Teranaka M Tezuka I Togawa H Ueda Y Ushida N Watanabe S Watanabe T Yokota J Yoon CS 《Physical review letters》1990,65(14):1729-1732
982.
983.
984.
M. Hattori Y. Ishikawa K. Mizuta S. Arai S. Sugimoto Y. Shimizu S. Kawanishi N. Suzuki 《Applied physics. B, Lasers and optics》1992,55(5):413-418
The infrared multiple-photon single-frequency decomposition (IRMPD) of CBrClF2 was examined as functions of laser wavenumber, laser fluence, and partial pressure of CBrClF2. The initial step was the scission of a C-Br bond. In the presence of O2 the carbon-containing product was CF2O and its subsequent hydrolysis gave CO2. The initial dissociation was highly 13C selective at wavenumbers below 1014 cm–1. CBrClF2 decomposed at relatively low fluences as compared to CHClF2. However, the decomposition yield rapidly decreased with increasing pressure. In the large-scale irradiation experiment using about 8 J pulse at 1 Hz, we obtained a carbon yield of 0.41 mol per pulse at a 13C-atom fraction of 17% for a mixture of 10 Torr CBrClF2 and 10 Torr O2, and a carbon yield of 0.17 mol per pulse at a fraction of 29% for a mixture of 20 Torr CBrClF2 and 20 Torr O2. The IRMPD of CHClF2 gave a carbon yield of 0.18 mol per pulse at 48% for 10 Torr neat CHClF2 and yield of 0.25 mol at 52% for 20 Torr CHClF2. The large-scale irradiation experiment was also carried out for mixtures of CBr2F2 and O2. CHClF2 is the most productive of 13C. 相似文献
985.
All six possible conformational isomers of the proximally p-dibrominated calix[4]arene tetraalkyl ether, 1a-f*, were selectively synthesized by appropriate control of stereochemistry during di-O-alkylation reactions of 5,11-dibromocalix[4]arene syn-dialkyl ethers, namely, 5,11-dibromo-27,28-dihydroxy-25,26-dipropoxy-, 5,11-dibromo-25,26-dihydroxy-27,28-dipropoxy-, 5,11-dibromo-25,28-dihydroxy-26,27-propoxy-, and 5,11-dibromo-26,28-dihydroxy-25,27-dipropoxycalix[4]arenes. Their conformations were confirmed by (1)H and (13)C NMR spectroscopy and are cone for 1a (u(Br)(Pr), u(Br)(Pr), u(H)(Pr),u(H)(Pr)), partial cone for 1b (u(Br)(Pr), d(Br)(Pr), u(H)(Pr),u(H)(Pr)) and 1d (u(Br)(Pr), u(Br)(Pr), u(H)(Pr),d(H)(Pr)), 1,2-alternate for 1c (u(Br)(Pr), u(Br)(Pr), d(H)(Pr),d(H)(Pr)) and 1e (u(Br)(Pr), d(Br)(Pr), d(H)(Pr),u(H)(Pr)), and 1,3-alternate for 1f (u(Br)(Pr), d(Br)(Pr), u(H)(Pr),d(H)(Pr)). Although both 1c and 1e are in the 1,2-alternate conformation, the conformation of 1e was found to be strongly distorted and distinct from that of 1c. 相似文献
986.
Takaishi S Tobu Y Kitagawa H Goto A Shimizu T Okubo T Mitani T Ikeda R 《Journal of the American Chemical Society》2004,126(6):1614-1615
81Br Nuclear quadrupole resonance (NQR) measurement was performed in an S = 1/2 one-dimensional Heisenberg antiferromagnetic metal complex [NiBr(chxn)2]Br2 (chxn: 1R,2R-diaminocyclohexane), having a halogen-bridged MX chain structure -Br-Ni3+-Br-Ni3+-Br-. Two 81Br NQR signals were observed below 40 K, while a single signal was observed above 130 K, showing the presence of two nonequivalent bridging Br sites below 40 K. This NQR result together with previously reported magnetic susceptibility and X-ray results indicate the occurrence of a transition into a spin-Peierls state between 40 and 130 K. This communication reports the first spin-Peierls transition in metal complexes in which pure d electrons contribute to the magnetism. In addition, we demonstrated a new experimental method for studying a spin-Peierls system. 相似文献
987.
H Kamiya T Sakaguchi N Murata M Fujimuro H Miura H Ishikawa M Shimizu H Inoue S Nishimura A Matsukage 《Chemical & pharmaceutical bulletin》1992,40(10):2792-2795
DNA templates containing a modified base (O6-methylguanine, 8-hydroxyguanine, xanthine or hypoxanthine) which was located in nucleotide sequences corresponding to the 12th or 61st codon of a ras gene were synthesized and deoxynucleotide incorporation opposite the lesions was investigated. The templates were replicated by Taq DNA polymerase, recombinant rat DNA polymerase beta and mouse DNA polymerase alpha-primase complex. Sequence analysis of the replicated products indicated selective incorporation of nucleotide(s) opposite a modified base, depending on the kind of base and of DNA polymerase. This system is very useful to obtain results of in vitro replication of modified bases in ras sequences. 相似文献
988.
Norio Kobayashi Akiko Osawa Hisao Kimoto Yasuo Hayashi Kiwako Shimizu Tamotsu Fujisawa 《Journal of polymer science. Part A, Polymer chemistry》1977,15(1):39-49
Thiuram polysulfide polymers have been prepared from alkali metal bisdithiocarbamates either by oxidation with ammonium persulfate or by polycondensation with sulfur chlorides. In some cases, isothiocyanate formation and/or thiourea formation were noticed. The polymer properties were significantly affected by the diamines used. Polymers derived from p-phenylenediamine decomposed gradually at room temperature with the liberation of elemental sulfur. Polymers based on aliphatic primary diamines were more stable. Piperazine gave the most stable polymer. 相似文献
989.
Kyoko Shimizu Frances Helen Blaikie Mikkel Kongsfelt Kristian Damgaard Schøler Sørensen Steen Uttrup Pedersen Kim Daasbjerg 《Journal of polymer science. Part A, Polymer chemistry》2016,54(1):91-98
A simple electrochemical approach based on potential sweeping has been developed for growing poly(phenylene sulfide) (PPS) brushes from 4,4’‐disulfanediyldibenzenediazonium salt on glassy carbon and stainless steel. First, the diazonium salt becomes reduced at the substrate on the initial part of the sweep carried out in a negative direction to form a covalently bonded diphenyl disulfide film. Once sufficiently extreme potentials are reached the disulfide bridges are reductively cleaved to form a thin layer of covalently attached thiophenolates. These are prone to be involved in fast coupling reactions with the diazonium salt to form PPS brushes in a repetitive growth process. In this manner linear PPS brushes with thicknesses up to 150 nm are easily formed. In addition, exact control on the brush length may be exerted through the switching potential selected or the number of sweeps applied. The films are characterized by time‐of‐flight secondary ion mass spectrometry which shows that the film growth is accompanied by an increase in the intensity ratio of S?/ in line with the proposed PPS structure. This structure was further supported by Raman spectra, exhibiting a high‐intensity C?S stretch band and no S?S stretch band. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 91–98 相似文献
990.
Prof. Dr. Masaki Shimizu Kenta Nishimura Rika Hirakawa Dr. Tsuneaki Sakurai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(5):1626-1637
The design and development of organic luminophores that exhibit efficient ultraviolet (UV) fluorescence in the solid state remains underexplored. Here, we report that 1,4-dialkenyl-2,5-dialkoxybenzenes and 1,4-dialkenyl-2,5-disiloxybenzenes act as such UV-emissive fluorophores. The dialkenyldioxybenzenes were readily prepared in three steps from 2,5-dimethoxy-1,4-diacetylbenzene or 2,5-dimethoxy-1,4-diformylbenzene via two to four steps from 1,4-bis(diethoxyphosphonylmethyl)-2,5-dimethoxybenzene. The dialkenyldioxybenzenes emit UV light in solution (λem=350–387 nm) and in the solid state (λem=328–388 nm). In addition, the quantum yields in the solid state were generally higher than those in solution. In particular, the adamantylidene-substituted benzenes fluoresced in the UV region with high quantum yields (Φ=0.37–0.55) in the solid state. Thin films of poly(methyl methacrylate) doped with the adamantylidene-substituted benzenes also exhibited UV emission with good efficiency (Φ=0.27–0.45). Density functional theory calculations revealed that the optical excitation of the dialkenyldimethoxybenzenes involves intramolecular charge-transfer from the ether oxygen atoms to the twisted alkenyl-benzene-alkenyl moiety, whereas the dialkenylbis(triphenylsiloxy)benzenes were optically excited through intramolecular charge-transfer from the oxygen atoms and twisted π-system to the phenyl-Si moieties of each triphenylsilyl group. 相似文献